1. Field of the Invention
The present invention relates to a disk cartridge which accommodates, in the interior thereof, a recording disk for recording of information.
2. Description of the Related Art
(Prior Art 1)
With disk cartridges for the recording and playback of digital information such as characters, graphics or the like, there is the concern that the disk cartridge may malfunction due to dust or dirt or the like adhering to the surface of the recording disk. Thus, the disk cartridge is provided with a shutter which shields a window portion which is for a recording/playback head or a spindle to access the recording disk.
Usually, the shutter opens and closes the window portion by being slid in the direction orthogonal to the direction of insertion of the disk cartridge. This sliding of the shutter is realized as follows: after the disk cartridge is inserted into a drive device, when the disk cartridge sinks therein, a shutter opening/closing member of the drive device catches on a shutter operation portion of the shutter, and slides the shutter in the opening direction or the closing direction.
In an ultra-compact disk cartridge such as DataPlay (which is the commercial name of a product), the recording/playback head of the drive is relatively large as compared with the size of the shell. Thus, when, due to the opening operation of the shutter, the shutter opening/closing member provided at the drive device approaches the window portion region of the shell, there is the concern that the shutter opening/closing member will advance into the region of operation of the recording/playback head.
In order to overcome this problem, a structure has been conceived of in which the shutter operation portion is provided in a vicinity of the window portion region of the shutter. As the shutter slides, the shutter opening/closing member, together with the shutter operation portion, withdraws from the window portion region of the shell. However, here, there is the possibility that, in the initial stages of opening of the shutter, the shutter opening/closing member will interfere with the recording/playback head.
In this way, in the conventional shutter structure, there is the possibility that the shutter opening/closing member will advance into the region of operation of the recording/playback head (i.e., the window portion region).
(Prior Art 2)
In disk cartridges such as 3.5-inch flexible disks (FDs), mini-disks (MDs) and the like, a recording disk which is an information recording medium is accommodated within a cartridge case. At the time of reading or recording information from or onto the recording disk, the recording portion or the reading portion at a disk drive device (hereinafter, “drive device”) can access the recording disk from a window portion of the cartridge case. Further, a shutter member is provided at the cartridge case. If the disk cartridge is not loaded in a drive device, the shutter member is at a closed position, and closes the window portion. As needed, the shutter member is driven by a shutter opening/closing mechanism of the drive device, so as to reach an open position, and the window portion is opened. There are shutter opening/closing mechanisms of drive devices which, for example, open and close a shutter member by engaging a shutter opening/closing lever, which is formed in a pin-shape or a plate-shape, with the shutter member, and moving the shutter opening/closing lever along the opening/closing direction of the shutter member.
In recent years, the development of small-sized disk cartridges has advanced as such small-sized disk cartridges are utilized in mobile devices such as cellular phones and the like. The cartridge case of such a disk cartridge is of course also made smaller-sized. Thus, there is a strong need to reduce the size of the parts and decrease the number of the parts accommodated within the cartridge case. Further, in order to make the information storage amount per recording disk as large as possible, there are cases in which both obverse and reverse surfaces of the recording disk must be used as information recording surfaces. In such a disk cartridge, usually, a window portion is formed in each of the obverse and reverse surfaces of the cartridge case. Shutter members, which open and close the window portions, are provided at the obverse surface side and the reverse surface side of the cartridge case. Accordingly, there is the need to provide spring members, which urge the pair of shutter members toward their respective closed positions, within the cartridge case in order to prevent the pair of shutter members from erroneously opening, and in order to return the shutter members, which are at their open positions, to their closed positions when the disk cartridge is discharged from the drive device.
However, if a pair of independent spring members for urging the pair of shutter members to the closed positions are provided within the cartridge case, the spring members must be made extremely small. Manufacturing of such small-sized spring members is difficult, and the manufacturing costs thereof are high. Moreover, the work for reliably assembling the small-sized spring members at predetermined positions within the cartridge case is difficult.
(Prior Art 3)
Conventionally, in 3.5-inch flexible disks (FDs) , mini-disks (MDs) and the like, a disc-shaped disk medium is accommodated within a case. At the time of reading or recording information from or onto the disk medium, a recording member or a reading member of a drive device accesses the disk medium from an opening portion of the case. Further, a shutter member is provided at the case. In the usual state, the shutter member is at a closed position and closes the opening portion. As needed, the shutter member is moved by a drive device to reach an open position, and the opening portion is opened.
Here, in order to prevent the opening portion from being opened needlessly, it is preferable to provide a locking member, for locking the shutter member, at the case. However, for example, in a case corresponding to a disk medium at which information can be recorded at both sides thereof, shutter members are provided independently at the two opening portions of the obverse and reverse sides. Thus, if lock members are provided separately for these shutter members, the number of parts increases, which leads to an increase in the costs for parts.
Moreover, because the number of work processes for assembling parts increases due to the increase in the number of parts, the assembly costs also increase. In addition, in recent years, it has become desirable to make disk media smaller sized. When, in accordance with this trend, the respective parts are also to be made small-sized, the assembly work becomes even more difficult.